1. Field of the Invention
This invention relates to a sinker actuating apparatus for a flat-knitting machine, and more particularly, to an apparatus for moving a sinker disposed on a needle bed back and forth in response to movement of a knitting needle.
2. Description of the Related Art
A flat knitting machine of the type wherein each of knitting needles is moved back and forth by an actuator such as a linear motor includes a plurality of movable sinkers which prevent needle loops from riding up together with tile knitting needles upon back and forth movement of the knitting needles, particularly from riding up upon forward movement of the knitting needles. Each of the sinkers is moved by an actuating apparatus in response to back and forth movement of a corresponding one of the knitting needles between a pressing position for pressing a knitted fabric and a releasing position for releasing the knitted fabric. It is to be noted that, in the present invention, a movement of a knitting needle in a direction to be projected from the position of a knitted fabric is referred to as forward movement or advancement, and a movement of the knitting needle in the opposite direction to be retracted from its projecting position toward the knitted fabric is referred to as backward movement or retraction.
One of movable sinker actuating apparatuses of the type described above is disclosed, for example, in Japanese Patent Appln. Public Disclosure No. 5-10247 which includes sinker actuating means disposed so as to move forward and backward on a needle bed Lo displace sinkers between a pressing position and a releasing position, connecting means for disconnectably or non-fixedly connecting the sinker actuating means to needle moving means provided for moving knitting needles back and forth, to move the sinker actuating means in response to movement of the needle moving means, and a forward positioning stopper and a backward positioning stopper for restricting an advanced position and a retracted position of each of the sinker actuating means, respectively.
According to the actuating apparatus described above, however, since each of the sinkers is merely displaced to tile pressing position upon forward movement of the corresponding knitting needle, a knitted fabric is not pressed by the sinker when a needle loop is to be formed or when the knitting needle is at a position a little advanced after formation of a needle loop, that is, when the knitting needle is retracted to a standby position. As a result, upon formation of a needle loop of a particular loop size, the needle loop cannot knock over, or during a standby condition of the knitting needle, a loop formed at the previous time, that is, an old loop, may ride up, resulting in formation of a swollen portion of the knitted fabric. The frequency of such phenomenon increases as the knitting pattern becomes complicated such as when a fabric of a pattern having great ups and downs is to be knitted or when knitting is performed locally.